Automated license plate readers (ALPRs) have become a widespread surveillance tool across the United States, with an estimated 119,000 readers in operation, according to a community-powered map. Flock Safety cameras represent approximately 83% of these mapped devices. While law enforcement agencies highlight their utility in locating stolen vehicles and aiding investigations, privacy advocates express concerns about the potential for mass data collection and the erosion of personal privacy.
These cameras, often mounted on poles, capture images of passing vehicles and use software to read license plates, converting them into searchable records. Each record can include the plate number, vehicle make, model, color, body type, and even notable visible features like a roof rack or bumper sticker. Crucially, the system also logs the time and location of the sighting. This data, when aggregated, can create a detailed log of an individual's movements.
California leads the nation in the number of mapped readers, with over 16,000 devices, particularly concentrated around the Los Angeles and Bay Areas. Other states with significant numbers of ALPRs include Florida, Georgia, and Illinois. However, the DeFlock map's reliance on public submissions means that populated areas may appear to have more cameras than rural regions, and the total number could be higher.
Law enforcement agencies utilize ALPR data to identify vehicles associated with crimes. Plates linked to stolen cars or active investigations can be placed on a hotlist, triggering an alert when detected by a camera. This can assist in recovering stolen property or locating missing persons' vehicles. For instance, a recent LAPD review identified 337 instances where ALPR alerts helped recover stolen vehicles, though the system also produced 161 incorrect 'stolen' plate flags over two months.
Despite their investigative benefits, privacy advocates warn that the widespread deployment of these cameras creates a de facto surveillance network. The ability to track vehicles without a warrant raises constitutional questions, particularly regarding mass data collection. Concerns also extend to data sharing between agencies, including potential access by federal or out-of-state entities.
In California, state law specifically restricts the sharing of ALPR data by local law enforcement agencies with federal or out-of-state entities. However, allegations have surfaced of violations, such as the lawsuit filed by California Attorney General Rob Bonta against the city of El Cajon for allegedly sharing data with over 100 out-of-state agencies.
The Los Angeles Police Department (LAPD) recently allowed its three-year operating agreement for Flock Safety cameras to lapse in July 2026. Officials cited concerns over data ownership, privacy, security, and clearer limits on how Flock could store and share collected information. While the cameras continued to operate, LAPD lost regular access to the data pending negotiations for a new agreement with stronger safeguards, including city ownership of all captured data and prohibitions on Flock using the data for commercial purposes or AI training.
Flock Safety asserts that its system does not continuously track vehicles and that authorized agencies can search for separate sightings. The company states its default data retention period is 30 days and that customers control their information and sharing settings. However, public records laws can complicate data access, as demonstrated by a Washington state ruling that ALPR images stored by a private vendor for a city could be considered public records.
Experts suggest individuals can learn about ALPRs in their communities by checking the DeFlock map, reviewing local ALPR policies for data retention rules, and inquiring about data-sharing agreements with other agencies. Understanding contract terms before camera installation and knowing who is responsible for reviewing data for misuse are also recommended steps for community oversight.